This invention relates generally to fused chemical baths having means to supply make up chemicals in solution thereto, and more particularly to means and apparatus for utilizing chemicals in solution as additions to fused chemical metal treating baths.
There are many processes where fused essentially nonaqueous chemical baths are utilized, and to which make up chemicals must be added periodically. One particular process is that which utilizes fused baths for treating metal for scale removal, or other surface conditions. In these processes, it is necessary to periodically add more chemicals to maintain the bath, making up for depletion due to drag out, chemical utilization, evaporation, and other bath losses. Conventionally this make up chemical material is added in granular, or flake, or other similar solid form, either as a mixture of the desired chemicals, or as a solid solution.
It has long been recognized that there could be substantial benefits if the make up chemical could be supplied in liquid form, but this has not been feasible here-to-for. It is just technically and economically not feasible to maintain and supply the make up material in fused anhydrous form; and, aqueous solutions of the material, if added to a fused bath above 100.degree. C., will result in an "explosion" due to the vaporization of the water into steam. However, liquid additions would afford close control of composition, essentially continuous addition, as well as many other benefits.